This invention lies in the field of fluid check valves. More particularly it concerns the type of check valves which have limited axial thickness, and are adapted to be inserted into a flow line, and clamped between opposed spaced flanges.
Still more particularly, this invention lies in the field of check valves which have self energizing seals, and can withstand back pressure without leaking fluid, even at low back pressures.
In the prior art check valves have generally been designed with planar sealing surfaces, and some sort of thin planar gasket means. Because of the nature of the seal, such valves require excessive back pressure to effectively seal fluid flow in the back direction.